electricity question-flickering LED illuminated switch.

[tokugawa]

Three way 120v circuit controlling some flood lights. Has two widely separated illuminated switches, the type with the toggle lit when the floods are off, so the toggles can be seen in the dark.
One of the toggles has a constant flickering. The connections have been checked for tight and the switch replaced. The other one is a steady glow.
 I stuck a volt meter on the power side and could detect no changes.
 This has been like this since the house was new,(20years) but I would love to figure out what is causing it. Any ideas?

[Firethorn]

Was the lit portion of the toggle itself replaced, and it keeps flickering, or just the switch?

Anyways, LEDs are diodes -they only light up when power is flowing the right way.  So the usual way is to use a 'slow' LED and just let the human brain smooth over that the thing is actually off about 70-80% of the time.  This is why LED Christmas lights can look weird.

Otherwise, well, the way to get a 'steadier' LED is to first, put a rectifier in - now the LED is on 40-60% of the time, and flickering at 120Hz, not 60Hz.  Much less visible.  The next step would be to include a capacitor. 

Or you could include 2 diodes and a capacitor, and if the capacitor is bad, you'd get the flickering.

SHORT:  The switch could be bad.

[Triphammer]

Lighted handle switches are almost never LED. Usually neon and neons flicker, can't be helped.

[never_retreat]

They are usually neon bulbs.
Consider any the don't flicker odd and say nice things to it.

[RocketMan]

Twenty years old?  A neon bulb in the switch, not LED.  Neon bulbs will start to flicker as they age.
I'd say replace the switch with another illuminated one, but can you even get switches with neon bulbs in them any more?

[tokugawa]

Hmmm, I assumed it was an LED.    The rate of flickering is variable and not even.
The switch was either completely replaced, or traded with the other one that does not flicker, as a test- I can't remember which, but it did not stop the flickering.
 it does not bug me bad enough to add any circuitry to it, the box is full enough anyway.

[Marnoot]

Every neon-illuminated switch I've had has had some flickering, even new out of the box. As mentioned, it's just what they do.

[Brad Johnson]

Last time I was at Home Despot I recall seeing several illuminated switches from old fashioned toggles to fancy flat ones. Simple swap.

Brad

[K Frame]

I've got an illuminated toggle switch in the utility room in my basement. It's been there 20 years and has never flickered.

[230RN]

Over time, the small amount of radon they put in neon bulbs (to both lower and stabilize the "ignition" voltage) decays to ineffectiveness.

This effect is similar to tritium-activated night sights decaying to half-effectiveness over 12 years.

I believe the half-life of the main isotope of radon they put in the bulbs is a little over ten years.

No cure except to replace the switch or get used to the flickering, which will only get worse.

The flickering will not affect the operation of the switch itself. But over time, the switch itself might wear out mechanically.

However, at this late date, I'm not sure they even sell neon-illuminated switches  any more.

Terry, 230RN

[birdman]

Over time, the small amount of radon they put in neon bulbs (to both lower and stabilize the "ignition" voltage) decays to ineffectiveness.

This effect is similar to tritium-activated night sights decaying to half-effectiveness over 12 years.

I believe the half-life of the main isotope of radon they put in the bulbs is a little over ten years.

OH GOD NO.
I'm sorry, but no, radon isn't used in...ANYTHING!

First off, the MOST stable isotope doesn't have a half life of anything close to years, it's a bit less than 4 DAYS, that's why it's such a PITA, because that's just enough time for it to diffuse out of the ground, get breathed in, and decay into the Pb/Po decay chain...3 more alphas and whammo, Po-210 and lung cancer.

IF there is anything radioactive in neon tubes (and other than Krytons, and some Hydrogen-based thyratrons, NO discharge tube uses radioactive material) to encourage a discharge, it would not be a gas, as that would be a contamination disaster waiting to happen.  It's why no one uses Krytons for anything really, and why the radioactivity stabilized thyratrons use radioactive Nickel on one of the electrodes.

I think the most radon ever contained in one place is something less than nanograms.
(Bear in mind, it's a product of the Uranium decay chain...so that means you are trying to establish an equillibrium concentration with a 4+ billion year half-life on one side, and a <4 day one on the other...or effectively 10^16th to one)

[230RN]

From the GE glow lamp manual:  "In darkness these [ionization] times may be reduced by the use of radioactive additives. (p.4)"  And on page 5, "One means for greatly reducing this 'dark effect' is the use of mild radioactive additives, which is being done for a large number of General Electric glow lamps."

As a matter of recollection, I believe the same is (or maybe was) true of Sylvania gas lamps, and I believe the same is (or was) true of photographic xenon flash lamps.

Obviously they did not add the radon from a lecture bottle of the stuff :eek:, but used other elements which decayed into radon somewhere along the line.  Thorium or thorium oxide comes to mind.  Nevertheless, the essential "active ingredient" mixed in with the neon was stated as radon, and helped stabilize the "firing voltage" under varying ambient conditions, including the dark effect.

I was wrong on the 10 year half-life. I misread the 3.000+ days as 3,000+ days.  Kind of struck me as odd, but I failed to check it.  Duh.

Terry

REF (The only one I can find at this late date):
General Electric Glow Lamp Manual, produced by the Miniature Lamp Department of G.E., copyright 1965.

[RocketMan]

You keep old data manuals around too, Terry?  Glad I'm not the only one.

[birdman]

From the GE glow lamp manual:  "In darkness these [ionization] times may be reduced by the use of radioactive additives. (p.4)"  And on page 5, "One means for greatly reducing this 'dark effect' is the use of mild radioactive additives, which is being done for a large number of General Electric glow lamps."

As a matter of recollection, I believe the same is (or maybe was) true of Sylvania gas lamps, and I believe the same is (or was) true of photographic xenon flash lamps.

Obviously they did not add the radon from a lecture bottle of the stuff :eek:, but used other elements which decayed into radon somewhere along the line.  Thorium or thorium oxide comes to mind.  Nevertheless, the essential "active ingredient" mixed in with the neon was stated as radon, and helped stabilize the "firing voltage" under varying ambient conditions, including the dark effect.

I was wrong on the 10 year half-life. I misread the 3.000+ days as 3,000+ days.  Kind of struck me as odd, but I failed to check it.  Duh.

Terry

REF (The only one I can find at this late date):
General Electric Glow Lamp Manual, produced by the Miniature Lamp Department of G.E., copyright 1965.

Having enough thorium (or any radon precursor) in there to make enough radon to make a difference would mean kilograms of the stuff.

I'm sorry, but nothing in what you posted says radon, or even radon precursor.  Especially given that the side-effect would be generation of Pb210 and Po210, which would be horrifying to have around.

Trust me, I just redid the math, it's not radon, or a radon precursor.  the only reasonable precursor would be Ra226, and that would be WAY more than anyone would want to have, or even be allowed to have around.

Sorry, as I said before, it may be radioactive, I EVEN GAVE YOU THAT,  though, usually not used anymore, as the hazards are an issue) it's just not radon or a radon precursor.

So argue all you want, it's not radon.  Do the math yourself if you want...or trust mine.  But I'll wager my almost two decades of nuke-E experience to your "read a manual that doesn't even say radon or what isotope it is", since you don't quote that part, just say that it says it's radon.

5 seconds of additional googling says it's usually Pm147, Th232, or tritium in modern ones.  Back then, I bet it was something else.  In any case, due to equillibrium aspects, the active ingredient is likely the longer loved one..not radon.  Actually, radioactive krypton would be the best choice...like they use in Krytons.

[230RN]

^ OK.

[Fitz]

Lighten up, Birdman :-D

[230RN]

You keep old data manuals around too, Terry?  Glad I'm not the only one.

Yeah, it's one of those things.  I even have old DOS manuals around.  Oh, and a Grainger's catalog and the last paper Radio Shack catalog they ever printed.  Sometimes there are nuggets in there. 

A tiny neurosis of mine. :)

One of the negative things I've noticed about the net is not that it's full of misinformation, but that it's full of incomplete information.

"Knowledge not transmitted is knowledge lost."

And I lost the information about who said that.

It figures.



Terry

[RocketMan]

Yeah, it's one of those things.  I even have old DOS manuals around.  Oh, and a Grainger's catalog and the last paper Radio Shack catalog they ever printed.  Sometimes there are nuggets in there.

Check, check and lotsa checks on the old RS catalogs.

[230RN]

On deep introspection, meditation, and self-examination after your post, I realized that it's like the comic book collector syndrome.

Someday there may be a store where nerds can come in and trade manuals... "I'll trade you your Grainger for two mint-condition, DOS manuals, 3.2 and 4.0, straight across.  How about it?"

Maybe combine it with a baseball card/comic book store.  Yee-haw !

Jump forward 10-15 years, and someone's bound to say something like, "I had a great collection of manuals and catalogues, but when I got married and moved out of the house, my mother threw them all away."

<Terry whistles for his brain to come back and puts it back on its leash.  Can't let it run around off-leash for too long, y' know.>

Terry, 230RN

[K Frame]

You got beat up a lot in school, didn't you?

[230RN]

Nah, it was a high-end entrance exam boys-only high school... which tended to eliminate boy versus boy over girl type encounters.  And the student body was essentially scattered from all over the city, rather than drawn from a local area.  So "territorial" high school versus high school stuff didn't happen.

In addition, there were only two subway stops nearby, and most of the 6000 students walked in large columns to the stations when they let us out at 3 PM.  No parking lots, so there was no place to gather and think up trouble after school. A small group of us used to hang out in a candy store near one of the subway stations to let the crowds in the subway station clear out a little.  The owner sold "loosies," which were single cigarettes, 3 cents each IIRC, and let us smoke them there.  (There were no laws about minors buying cigarettes then.)

Ninety-nine percent nerds anyhow, though the term wasn't in use then (late forties, early fifties).  And we were too busy trying to keep our academics up to get too aggressive.  

The admins did warn us to stay out of Williamsburg, known for its gangs.  The only fights I ever got into (losing, mostly) were in grade school, K-8.

Well, that's the way the thread drifts.

Terry

[birdman]

On deep introspection, meditation, and self-examination after your post, I realized that it's like the comic book collector syndrome.

Someday there may be a store where nerds can come in and trade manuals... "I'll trade you your Grainger for two mint-condition, DOS manuals, 3.2 and 4.0, straight across.  How about it?"

Maybe combine it with a baseball card/comic book store.  Yee-haw !

Jump forward 10-15 years, and someone's bound to say something like, "I had a great collection of manuals and catalogues, but when I got married and moved out of the house, my mother threw them all away."

<Terry whistles for his brain to come back and puts it back on its leash.  Can't let it run around off-leash for too long, y' know.>

Terry, 230RN

I'll trade you a vintage VAX 9000 original brochure set for a vintage Fairchild semiconductor catalog if you got one...

[230RN]

Don't got one, but is the Navy still using VAX machines? Maybe you could sell it to them.  Sold one out of my store for a pittance because it was taking up too much floor space.  I think they wanted it for spare parts.  Apparently the Navy was really locked into VAX machines for some reason.